As people become more clued in to the risk of skin cancer posed by sun exposure, and the use of sunscreen creams increases, researchers from the University of Gothenburg and Chalmers University of Technology began the search for a natural UV filter as they claim the use of sunscreen can give rise to contact allergy when exposed to the sun, and this has led to an increasing incidence of skin allergy.
"Unfortunately, several of the chemical UV filters used in sunscreens cause contact allergy, either of themselves or when they are exposed to sunlight,” explained Isabella Karlsson, research student in the Department of Chemistry at the University of Gothenburg.
“We have therefore studied a UV filter, scytonemin, that is found in certain bacteria. We have managed to produce this substance artificially in the laboratory.”
Scytonemin is produced by certain cyanobacteria that live in habitats exposed to very strong sunlight. It absorbs UV light and thus protects the bacteria from being damaged by the sun's radiation.
Karlsson pointed out that this natural UV filter has the potential to replace other filters that have been found to increase incidence of skin allergy, but added that more research will be required, however, before it can be added to sunscreen creams.
Karlsson also describes in her thesis, studies of a relatively new UV filter, octocrylene. She states the popularity of octocrylene has increased a great deal since it is not broken down by sunlight, and it stabilises other substances.
However, several reports of allergic reactions to octocrylene have appeared in recent years, with clinical studies and lab experiments suggesting that octocrylene can cause contact allergy, both of itself and when it is exposed to sunlight. Many patients who reacted by developing photocontact allergy to octocrylene developed photocontact allergy also to the drug ketoprofen.
"We tested 172 patients with suspected skin reactions to sunscreen creams and/or the drug ketoprofen in one of our studies. It turned out that 23 of these patients reacted to the UV filter octocrylene. Five of them were diagnosed with contact allergy and the other 18 with photocontact allergy," said Karlsson.